1. Field of the Invention
The present invention relates to an absorbance analyzer which comprises an optical detector for measuring an absorbance spectrum in relation to a chromatograph such as a gas chromatograph or a liquid chromatograph. This absorbance analyzer can be employed for analyzing absorbance of an effluent fluid sample from a chromatograph, for measuring time change of a specific functional group or the like.
2. Description of the Background Art
A Fourier transform infrared spectrophotometer (FTIR) is adapted to analyze absorbance of an effluent gas from a gas chromatograph, in order to form a chromatograaph by time change of an absorption peak of a specific functional group. In this case, the absorbance value is integrated in a prescribed wave number range having absorption of the specific functional group, thereby recording its time change. Assuming that the wave number range is set as .nu..sub.1 to .nu..sub.2 and absorbance spectrum waveform at a time t is represented by A(t, .nu.), the following value I' (t) is recorded: ##EQU1##
In general, a single organic substance has a plurality of functional groups every molecule, and absorbance spectra of such functional groups may be overlapped with each other in a certain wave number range. When a chromatogram is formed by wave number integration of absorbance in a conventional method, therefore, the as-formed chromatogram is not proportionate to only concentration of a single target functional group, but influenced by absorption of other functional groups in an adjacent wave number region, fluctuation of the base line of the absorbance spectrum, and the like. Thus, it is difficult to study the results of an analysis.